Motor Mount Mishap: How GM Pissed Off Nader (A Second Time)

Torque. Although big horsepower numbers seem to get all the glory, without the mass-moving capabilities of torque, horsepower would mean nothing. Let’s face it, torque moves mass and horsepower is what keeps it moving. Chevrolet was having an issue with the torque its engines were making back in the late ’60s and early ’70s, and that resulted in a recall of more than 6,680,000 1965 through 1970 Chevrolet cars. This was because they had what was deemed as defective engine mounts. You wouldn’t think the manufacturer would sell a lot of cars that had so much torque that they kept breaking engine mounts, but apparently…

mount

Early engine mounts did not have a safety provision in case the rubber isolator failed. If the rubber did come apart, the engine was free to travel up and down in the engine bay. That might sound catastrophic, but if the engine moved and the throttle opened because of the movement, things could get dangerous.

The National Highway Traffic Safety Administration (NHTSA) received its first reported incident about engine-mount breakage in September of 1969. The NHTSA then contacted GM a few weeks later, but an epidemic broke. Before GM could reply to the letter indicating that they had received a total of 14 reports concerning 1968 models, the NHTSA labeled the investigation inactive. The NHTSA informed GM of this inactive status in a letter sent in June 1970.

In late-August 1970, the NHTSA received another incident report. They then arranged independent testing to learn the effects broken engine mounts have on the driver’s ability to remain in control of a vehicle after breakage. But, many feel there was a flaw in the testing.

mount

The test facility used a Chevrolet vehicle that did not have power brakes or power steering. This “oversight” prevented experiencing brake-assist loss during mount failure. Nonetheless, the tests demonstrated the throttle-opening effect that consumers had noted. This testing prompted the NHTSA to send another, more in-depth information request to GM in December 1970. The company’s reply indicated a total of 172 incidents of failed engine mounts, resulting in 63 accidents and 18 injuries. The NHTSA did nothing with this information until June 1971.

That is when the administration sent questionnaires to 63 consumers who reported broken Chevrolet engine mounts. The NHTSA then sent a third letter to GM in August. Wanting to get his 15 minutes of fame, Ralph Nader also sent a letter to the NHTSA regarding the administration’s deficiencies in its investigative procedures, which included the handling of the engine mount defect.

The NHTSA sent another letter to GM on December 1, 1971, informing the company that it was close to determining that there was a motor vehicle safety defect. Three days later, GM announced a recall because of the mounts, but refused to admit that the vehicles contained a safety defect.

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1967-1969 Camaro and Nova Engine Lift Stop Cable Unit. GM part number 330265

In a December 5, 1971 New York Times article, “It is apparent that, as a result of the publicity that has been given to the engine mount issue, there is a great deal of misinformation and misunderstanding on the part of Chevrolet owners, which we are anxious to eliminate as soon as possible,” General Motors said. The article also stated, General Motors would not be able to begin making the repairs until the end of February, as that was the earliest it could obtain the names of car owners and could manufacture and deliver the repair parts to dealers. If anything should go wrong with an engine mount in the meantime, the company said, “The driver should turn off the ignition key and brake the vehicle to a stop.”

mount

Although GM used the cable to fix the recall, soon after, the mounts were redesigned to incorporate a safety tab that kept engine movement in check should the rubber fail.

Another statement from GM eluded that, “Only in rare instances does engine lift involve the throttle and become a problem following the engine mount separation.” The New York Times article finished by stating, “there is no practicable way of knowing when a motor mount is about to fail, and critics have complained that the cars have no system, such as the one the company plans to install, to keep the car under control if the mount fails. In announcing the recall, General Motors refused to answer any questions about the issue.

mount

Eventually, the clam shell-style mount was utilized. This style mount saw the rubber isolator encased as part of the frame half of the mount system.

Of the more than 95-percent of the vehicles recalled, GM did not actually replace the defective mounts. Instead, the company had dealers install a bracket and cable to restrict engine movement if a mount did break. By avoiding the replacement of $50.00 engine mounts on all 6,680,000 cars, GM managed to use the $1.00 part, cutting its recall costs considerably.

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About the author

Randy Bolig

Randy Bolig has been working on cars and has been involved in the hobby ever since he bought his first car when he was only 14 years old. His passion for performance got him noticed by many locals, and he began helping them modify their vehicles.
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